1. Field of the Invention
The present invention relates to means for ejecting or jettisoning loads from aircraft by utilizing the thrust produced by expanding gases, and has specific reference to an improved retractable telescopic device of this character.
In the devices disclosed in the U.S. Pat. Nos. 3,756,545 and 3,871,604, the surface area receiving the gas thrust is smaller at the end of the stroke than at the beginning thereof. Since, on the other hand, the gas pressure decreases as the telescopic device expands, a substantial discrepancy is observed between the initial thrust and the thrust produced at the end of the piston stroke on the load.
TO THE ENERGY NECESSARY FOR IMPARTING A PREDETERMINED SPEED TO THE LOAD THERE CORRESPONDS A SUBSTANTIAL REACTION EXERTED ON THE AIRCRAFT STRUCTURE DURING THE INITIAL PORTION OF THE MOVEMENT, THIS REACTION DECREASING AS THE STROKE INCREASES. In certain cases, this initial reaction is inconsistent with the strength of the aircraft structure, so that for imparting nevertheless the necessary velocity to the load a permissible thrust as constant as possible and in any case definitely lower that the peak thrust must be created while utilizing the same amount of energy.
Various arrangements have been developed with a view to obtain this result, for example by reducing the gas feed at the beginning of the movement and permitting a greater gas flow beyond a predetermined piston stroke. This method, consisting broadly in partially throttling the initial gas passage, is objectionable in that it is attended by a certain erosion of the throttled regions while promoting a dissipation of energy by increasing the heat exchange between the hot gases remaining for a longer time in contact with the wall surfaces located upstream of the device.
2. Description of the Invention
It is the essential object of the present invention to avoid the inconveniences mentioned hereinabove by allowing a free gas flow, with maximum efficiency, and compensating the pressure drop resulting from the gas expansion during the extension of the telescopic pistons through a concomitant and automatic increment in the cross-sectional surface area of the piston means on which the gas pressure is exerted.
In order to afford a clearer understanding of this invention, a first form of embodiment thereof, together with a modified construction, followed by a second form of embodiment will now be described, as illustrated in the attached drawings, in which: